A widely used tuberculosis vaccine may be a powerful tool for lowering A1c levels in patients with long-term diabetes.

The attenuated Mycobacterium bovis bacillus Calmette-Guerin (BCG) strain has been used as a vaccine against tuberculosis for more than 100 years, but now it's use is being investigated in patients with diabetes, according to a new study published in Nature Partner Journals.

Researchers investigated the impact of two doses of BCG vaccine in 211 patients with type 1 diabetes and 71 nondiabetic controls. The study was part of a prospective randomized eight-year examination. They discovered that after year 3, BCG lowered hemoglobin A1c levels down to near normal levels in the patients studied. The study found a reduction in A1c levels of greater than 10% after year 3 and 18% at year 4. Those lower hemoglobin A1c levels were then maintained for the next five years, according to the study.

"It suggests that even for diabetics who have had the disease for many years there may be an intervention that can correct their blood sugars without risk of hypoglycemia," Denise L. Faustman, MD, PhD, a coauthor of the study, tells Drug Topics.

The study had two important findings, she says: first, that BCG had the ability to create a durable and significant change in blood sugar, and second, that BCG appears to be create a new and novel metabolic mechanism that increases cellular consumption of glucose.

The authors of the study noted a "systemic shift" in glucose metabolism in those who received the vaccine, moving from oxidative phosphorylation to aerobic glycolysis.

While the results of the examination are exciting, researchers still aren't sure why the BCG vaccine was so effective in lowering A1c levels. "Also, it is very important to note that not all strains of BCG are the same and do not have the same immune effect that the strains we are studying have," she says.

"There is a lot to learn about this new mechanism," Faustman says, who directs the Immunobiology Laboratory at Massachusetts General Hospital.

The next step to fully understanding the potential that BCG vaccine could have for patients with type 1 diabetes is to complete the Phase II trial. "We are actively trying to raise funds for an expanded access trial, as well as a pediatric trial," Faustman says.

BCG could play a powerful role in treating type I diabetes in the years ahead, but this area of research is relatively new. Faustman cautioned that BCG is not currently approved for type I diabetes and should not be used off-label by healthcare providers until it is approved by the FDA.